Field of the Invention
The invention relates to an open-end spinning apparatus in a spinning machine for continuous spinning of textile fibers being supplied to a spinning rotor through a respective delivery and opening device, the delivery and opening devices being disposed in a pivotably supported cap covering the spinning rotor, a pivot pin of the cap being oriented at right angles to the rotor axis, a shaft being installed in stationary fashion and extending longitudinally of the spinning machine for driving a multiplicity of opening devices, the opening device carrying a worm wheel on its drive shaft, and the worm wheel meshing with a worm mounted on the shaft being installed in stationary fashion when the cap is closed.
In open-end spinning apparatuses, as a rule both the delivery and the opening devices are accommodated in a cap located in front of the respective spinning means. This cap is hinged at a pivot pin and can be raised, making the spinning means accessible. However, raising it also makes the delivery device for the sliver and the opening device, that is, the opening roller, accessible as well. The corresponding devices can easily be cleaned and replaced by opening the hinged cap. That kind of device is known, for instance, (not prior art), from German Published, Prosecuted Application DE-AS 23 14 229.
In contrast to textile machines with an individual drive, open-end spinning apparatuses as a rule have drives that drive all of the identical working means in the respective spinning stations jointly. That is true, for instance, for sliver draw-in rollers and for openings devices. The drive shaft for the draw-in rollers extends through the entire machine and there is a worm at each spinning station that drives a worm wheel having a shaft on which the draw-in roller is seated. If the cap of a spinning station is opened, the worm wheel swivels out of the particular worm that drives it and is thus disconnected from the drive.
If the cap is closed again and the worm wheel that drives the opening roller of the draw-in device is to be put back into engagement with the worm again, then the teeth may not mesh because the tooth tips are jammed together. Given the usual gear ratios of a worm gear for driving an draw-in roller, which range from 1:15 to 1:30, the pitch dimension measured along the tips of the worm wheel at the tip circle is greater than the pitch dimension of the worm. This is because the pitch of a worm and the pitch measured at the pitch circle diameter of the worm wheel are the same, but the pitch measured along the larger tip circle diameter of the worm wheel is greater. As a result, when the worm wheel plunges into the worm, especially if there is an unfavorable gear ratio, a situation can arise where two teeth of the worm wheel contact the thread or two teeth or threads of the worm, or overlap them and become wedged. In those positions, even if the worm revolves, full engagement does not occur.
German Published, Prosecuted Application DE-AS 23 14 229 therefore discloses a special embodiment of the worm wheel. Moreover, the pivot point for the cap is located in such a way that the worm wheel pivots at a tangent into the worm. By constructing the teeth specially and by providing an elastic peripheral zone for the teeth, damage to the driving wheel is averted.
However, it is logical to construct the drive wheel in that way only if a tangential introduction of the drive wheel into the worm is possible.
However, for structural reasons it is not always possible to place the cap in such a way as to enable tangential introduction of the worm wheel into the worm, and therefore it is usual to provide for the conventional vertical or virtually vertical plunging of the drive wheel into the worm. That kind of vertical or virtually vertical plunging of the drive wheel into the driving worm is known from German Published, Non-Prosecuted Application DE 43 23 213 A1, corresponding to U.S. application Ser. No. 08/273,861, filed Jul. 12, 1994.